1. Field of the Invention
This invention concerns foundations, and more particularly, foundations which are particularly adapted to provide support for manufactured structures, such as mobile homes, and also concerns methods of installing such structures on foundations.
2. Description of the Prior Art
The evolution of manufactured or factory-built housing, from temporary buildings such as mobile homes moved relatively often from site to site into an alternate form of permanent construction has contributed in no small way to the inefficiencies of support designs for such structures. The original approach when such mobile homes were truly "mobile", was for the mobile home to merely be placed on blocks, such as loose piles or concrete blocks, by jacking up the mobile home structure and lowering it onto the blocks. Since overturning forces applied by high winds must be resisted, tie-downs of various types are commonly employed. As a semi-permanent or permanent installation, this arrangement has numerous disadvantages: the tie-downs, makeshift in nature, do not provide adequate resistance to the overturning forces of the wind, and sometimes create structural damage by the resulting imposition of wind loads at the points of connection to the mobile home. In addition, the ground clearance required for installation of such tie-downs generally results in a high ground clearance increasing the area presented to the wind and its tendency to overturn, and which for aesthetic reasons is objectionable. In addition, it requires the use of extensive skirting paneling and stairways, etc. which also increases the cost of installing such units.
Furthermore, this support arrangement does not provide adequate resistance to vertical and lateral movements of the soil, occuring as a result of mud, frost, thawing, etc., such that the mobile home would not be securely positioned at level.
These deficiencies have resulted in efforts to provide a more secure support arrangement for such structures, but none of these arrangements has resulted in a foundation which is entirely satisfactory in all respects.
U.S. Pat. No. 3,664,082 discloses a foundation arrangement in which there is provided a concrete slab in which are embedded a plurality of piers which carry mounting studs which are used to bolt down the I-beam underframe of the mobile home to the pier. This approach, however, presents considerable difficulties in installation of the mobile home, since the bolting of the support must be carried out when the mobile home is lowered on the pad with less than minimal working room for the workers to perform their tasks. Indeed, the appraoch shown in that patent would not appear to be applicable to mobile homes having box beams as the underframe members, as opposed to the I-beams shown in that patent, since access would be impossible to the space beneath the mobile home intermediate the box members once the mobile home has been lowered onto the support surface.
In addition, the jacks used to raise and lower the mobile home must be provided in an excavated clearance space beneath the mobile home, further adding to the difficulties of installation, and creating drainage difficulties.
Another approach is described in U.S. Pat. No. 3,708,931 in which a very extensive concrete foundation is provided with a large well extending down into the ground with a service access cavity to in effect provide a "basement" for the mobile home. This very extensive reinforced concrete structure could, of course, be quite expensive, and to some extent defeating the purpose of the mobile home approach of providing low cost shelter units.
U.S. Pat. No. 3,830,024 discloses a plurality of piers with a telescoping mounting arrangement to allow leveling of the mobile home on the piers. The resulting height of the mobile home is still undesirably great. Additionally, the pier supports for the mobile home are not "laterally stablized" with respect to the earth, that is while the piers presumably would be emplaced at a depth in the ground which would provide adequate support against vertical movement of the piers due to the freezing and thawing of the earth, such piers are not restrained from lateral movement of its upper portion due to such freezing and thawing. Thus, if they were installed at a date much prior to the installation of the mobile home, and if freezing of the earth had taken place in the interim, the mounting structure could be misaligned by virtue of the vertical shifting of these piers, such as to prevent installation of the mobile home. Furthermore, if the pier structure were installed just prior to the installation of the mobile home, the resulting lateral movement of the piers would misposition the mobile home.
Many support arrangements utilized in the past are not applicable to frame beam spacings other than the standard 76 inches and thus are not universally applicable.
Accordingly, it is an object of the present invention to provide a foundation arrangement for such manufactured structures which provides a foundation at grade to support the mobile home structure so as to resist any lateral movements of the foundation resulting from movements of the earth at the surface and also adequately resists overturning forces produced by wind gusts.
It is another object of the present invention to provide such a foundation arrangement which supports the mobile home at a minimum ground clearance to reduce the wind induced overturning forces, and also improve the aesthetic appearance of the mobile home, and eliminates the need for extensive mobile home skirting.
It is yet another object of the present invention to provide such a foundation arrangement which allows the mobile home to be mounted to the foundation with relatively easy access to the undercarriage during such installation.
It is still a further object of the present invention to provide such a foundation arrangement in which the costs of preparing the foundation are kept to a minimum.
It is yet another object of the present invention to provide such a foundation arrangement and method of installation of the mobile home which does not require excavations for the jacks used to raise and lower the mobile home into position.
Another object of the present invention is to provide such a foundation arrangement having universal application.
Yet another object is to provide a foundation arrangement and installation procedure which allows removal of the running gear to reduce the cost of the installed mobile home.